화학공학소재연구정보센터
Materials Chemistry and Physics, Vol.114, No.2-3, 576-579, 2009
Dielectric properties of nanocrystalline Pb0.8Sr0.2TiO3 thin films at different annealing temperature
Nanocrystalline Pb0.8Sr0.2TiO3 (PST20) thin films have been synthesized by metallo-organic decomposition (MOD) technique and deposited on Pt/Ti/SiO2/Si substrates at different annealing temperatures of 550-750 degrees C. The X-ray diffraction (XRD) confirms the distorted tetragonal perovskite phase in PST20 films. The average grain's size varies from 35 nm to 46 nm as the annealing temperature increases from 650 degrees C to 750 degrees C as revealed by atomic force microscopy. At 550 degrees C, the film shows low crystallization with incomplete perovskite structure. The study of dielectric properties of PST20 films is aimed at electrically tunable applications and to observe ferroelectric behaviors of PST20 films. The film annealed at 650 degrees C shows large dielectric constant and higher tunability than the films annealed at 550 degrees C and 750 degrees C. The values of dielectric constant and tan delta at 1 MHz are 272 and 0.005, respectively, and tunability is similar to 66% for PST20 film annealed at 650 degrees C. The dispersionless dielectric properties are observed up to high frequency similar to 8 MHz. The results suggest that the growth of uniform, dense and nano-sized grains in PST film makes it suitable for higher frequency device applications and electrically tunable devices. (C) 2008 Elsevier B.V. All rights reserved.